Maybe several hay bales. To make them last longer I'd try to set them on something that allows some air to get under them like pallets and cover them with a tarp when not being used. If you could find a big piece of thick stryofoam or connect some pieces together that might work, and be easier to move and not be such an eyesore.
Walk the night, travel light, cross the Rio Grande
Someone strums a mandolin, soft gulf breezes blow
My new life is waiting in old Mexico
-Robert Earl Keen